Don,
Although I have been fairly active in gauge one live steam, I am not into collecting so can't help much. But I know two people who might be able to help you find a knowledgeable person. Dan is a member of the group that publishes Steam in the Garden Magazine.
"Dan Pantages is very active in gauge one live steam and knows everyone. An email to him and he can probably recommend someone who is familiar with your engine.
Marc Horovitz, founder and editor of Garden Railways Magazine, is quite knowledgeable of older engines and may be able to help also. He may be contacted through the editorial department of Garden Railway Magazine. Here is a link to their editorial contact form. It's a pain to use I know but Marc keeps his private email address limited to personal contacts he knows.
I will send you a PM with Dan's email address as I don't want to put it on a public forum without permission. If you contact either of them you can mention my name as they are both good friends. Dan is a member of this forum but is not very active on it.
Gail in NM